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What is going on at Mansfield dam?


TexasEd

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Reading some of the responses got me thinking...if Mansfield was to sustain a complete failure, would the overall devastation be less if they were able to blow up Miller? In other words, would accepting that the places on the above map will be a total loss - and deciding to destroy Miller ASAP - ease enough pressure from the oncoming wave that the end result would be less total damage/death?

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I read a book about the Stuxnet virus that discussed how easy it is to hack command and control software and that we’ve run infrastructure tests that specifically demonstrated Hoover damn could be made to fail by taking over the software managing it.  The only saving grace being that the software is not connected to the internet.  You would need someone to infiltrate the dam to gain physical access to the computers to plant a virus via a USB stick or somesuch.

Anyway, it’s probably nothing.  Sleep well, folks!

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1 hour ago, Chet Steadman said:

I’m sure others exist, but what other major US cities would be affected as catastrophically as Austin in the event of a total dam failure?

Seems like we would be near the very top.  

That is another similarity Austin shares with Nashville:

https://en.wikipedia.org/wiki/Wolf_Creek_Dam

Largest reservoir east of the Mississippi. Total failure would put 30' of water in the Titans football stadium 150 or so miles downstream. 

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8 hours ago, Chet Steadman said:

I’m sure others exist, but what other major US cities would be affected as catastrophically as Austin in the event of a total dam failure?

Seems like we would be near the very top.  

Also I would think Bastrop and the other towns all the way to Matagorda would take a beating.  

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Pretty obvious it was a sighting of Asa Grumbles (Ghosts of LCRA)

One of the many hungry and unemployed masses seeking work during the Depression, Grumbles was a carpenter working on the installation of the concrete forms on the dam. One of the LCRA hands told me that Asa Grumbles had once played bass guitar with Ernest Tubbs before Ernest Tubbs became famous. But late on December 26, 1939, the day after Christmas on the night shift, 32-year-old Asa Grumbles was killed when a cable snapped and a load of wet cement opened above his head and submerged him in a concrete pour.

Rumors persist to this day that they did not get all of Asa Grumbles out of the dam.

They got Asa out of the concrete — witnesses do tell of seeing him lying in state and he is buried in the Fitzhugh cemetery — but rumors persist to this day that they did not get all of Asa Grumbles out of the dam. There are stories about a hand and a ring on that hand that did not make it out of the concrete. Grumbles left a young wife and two children.

 

 

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9 hours ago, SquishMitten said:

Reading some of the responses got me thinking...if Mansfield was to sustain a complete failure, would the overall devastation be less if they were able to blow up Miller? In other words, would accepting that the places on the above map will be a total loss - and deciding to destroy Miller ASAP - ease enough pressure from the oncoming wave that the end result would be less total damage/death?

The answer would depend on what level of failure Mansfield had and how it progressed. In imagination land, if you completely removed the dam as a whole in one instant, you would have over 1 million acre feet of water flowing into a river that holds like 25k acre feet (at pool elevation). So the impact of removing that volume of water is pretty inconsequential. There are too many factors involved to try and estimate the downstream impacts since it would wholly depend on the level of failure and the discharge rate of the failed section. 

Any substantial dam failure would likely result in the rest of the dam failing at a fairly rapid rate and the impact from here to the coast would be catastrophic. If it was PMP/PMF situation (say from a hurricane tracking upstream and camping in the watershed) that caused the failure, it would cause biblical flooding and the damage would be inconceivable. 

shocked the princess bride GIF

Edited by HOOKEM4
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2 hours ago, Texas007 said:

Pretty obvious it was a sighting of Asa Grumbles (Ghosts of LCRA)

One of the many hungry and unemployed masses seeking work during the Depression, Grumbles was a carpenter working on the installation of the concrete forms on the dam. One of the LCRA hands told me that Asa Grumbles had once played bass guitar with Ernest Tubbs* before Ernest Tubbs* became famous. But late on December 26, 1939, the day after Christmas on the night shift, 32-year-old Asa Grumbles was killed when a cable snapped and a load of wet cement opened above his head and submerged him in a concrete pour.

Rumors persist to this day that they did not get all of Asa Grumbles out of the dam.

They got Asa out of the concrete — witnesses do tell of seeing him lying in state and he is buried in the Fitzhugh cemetery — but rumors persist to this day that they did not get all of Asa Grumbles out of the dam. There are stories about a hand and a ring on that hand that did not make it out of the concrete. Grumbles left a young wife and two children.

 

 

Tubb, unless this is a world where Kenny Roger and Hank William are country stars. 

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9 hours ago, InkaUtexas said:

So a Texans fan? 

Absolutely not. I have been teamless in the NFL since 1997. It's weird -- I spent my childhood and early adulthood moving back and forth between Houston (where my family's from) and Nashville. From 1978-1984 I was one of the few Oiler fans in Nashville. Moved back to Texas for HS and college. Moved back to Nashville in 1995 and then back to Houston for good in 1997, the same year the Oilers moved to Tennessee. So my dad had his team move to him, but as the ExOilers, they were dead to me, and I have not bonded with the new Houston NotOilers at all. So 30' of water in both stadiums for all I care.

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Also I would think Bastrop and the other towns all the way to Matagorda would take a beating.  

Just based on my observations of the water level at bastrop back when the most recent flood hit travis (October '18?), Bastrop flooding would be severe at a minimum; there's a bit of storage in the floodplain between Austin and there, so the peak wouldn't be as bad (relatively speaking). There's significant storage in the floodplain between bastrop and wharton/bay city. Not sure how bad flooding would be down near the coast, but the river would certainly be flowing full in its main banks

 

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11 hours ago, Goredho said:

I read a book about the Stuxnet virus that discussed how easy it is to hack command and control software and that we’ve run infrastructure tests that specifically demonstrated Hoover damn could be made to fail by taking over the software managing it.  The only saving grace being that the software is not connected to the internet.  You would need someone to infiltrate the dam to gain physical access to the computers to plant a virus via a USB stick or somesuch.

Anyway, it’s probably nothing.  Sleep well, folks!

Edward Abbey's dream was to sink houseboats full of explosives against it and then blow it up.  Don't we have a Hayduke screen name around here?

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Ok I was wrong, after googling Mansfield Dam failure and ending up on a Homeland Security watchlist, I found the article below which points out that the flood projection map that was quoted earlier is a projection of a Mansfield Dam Failure. In short, if Mansfield ever fails we're getting a number six run on us and we'll be right fucked.  

 

Spoiler

Mansfield Dam Failure

Austin Flood Areas if Mansfield Dam Fails

At-Risk if Mansfield Dam Fails

  • $4+ Billion Dollars in Property
  • 35,918 People in 13,382 Housing Units (2004 fig.)
  • 108 Bridges
  • 6 Fire & Police Stations
  • 12 Schools, 1 Hospital, and 6 Toxic Sites

1 – Floodwaters would extend up to West 6th Street near Mopac
2 – Floodwaters would extend to Barton Creek Blvd
3 – Downtown would be flooded up to 5th – 7th Street
4 – East Austin would be flooded up 7th Street
5 – Floodwaters would extend to Riverside & Grove
6 – Floodwaters would extend to 12th & Airport
7 – Flooding would extend as far as Hwy 71 by ABIA

Mansfield Dam is located by 620 near Lakeway, West of Austin. It is the only dam meant to hold back floodwaters in the chain, making it incredibly important for Austin and downstream cities. If the dam were to fail it would unleash 1.1 Million cu. ft. of water per second.This high flow rate would also continue for a substantial amount of time due to the size of Lake Travis (1.1 Million acre-feet).

These projections take into account the subsequent failure of Tom Miller Dam since it cannot withstand the surge of floodwaters. Needless to say, Austin would be heavily affected by a flood of this magnitude, with the potential loss of life in the thousands and the large-scale destruction of Central Austin.

The shear destruction by the initial wave of water will be catastrophic. Depending on the size of the breach, a wall of water will be blasted out at speeds in excess of 1,000 MPH and could still be traveling at 50 MPH by the time it reaches Austin. In the Teton Dam failure, initial wave velocity was 1,090 MPH (1,960 ft/s) and the wave was 120 ft tall. The St. Francis Dam failure was an instantaneous failure and released an initial wave of water at 2,018 MPH (2,960 ft/s). These velocities are the result of massive amounts of pressure being created by the weight of the water.

The energy within a huge body of water moving at even 20 – 30 MPH are sufficient to obliterate most structures including high-rises and bridges. Even if a structure withstands the initial impact, it must also survive being subjected to continuous force from the waters rushing by, debris strikes, and the potential erosion of the foundation. As we saw in the FM 2900 bridge collapse, the water is more than capable of tossing around entire sections of a bridge like it was a raft.

Research & Source Links

LCRA Dams & Lakes
LCRA Dam Failure Report (PDF)
H20 Partners (Visuals)
FEMA Dam Safety & Failure Report (PDF)

 

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23 minutes ago, ShaggyBevo RIP said:

Edward Abbey's dream was to sink houseboats full of explosives against it and then blow it up.  Don't we have a Hayduke screen name around here?

Abbey really was dreaming, as the reinforced concrete of Hoover Dam is 660’ thick at the base and tapers to 45’ thick at the crest,

Considering the level of Lake Meade is at least 100’ below the crest, and sinking a fleet of explosive-laden houseboats down to a thicker part of the dam, I’d say that venture would be nigh impossible, unless a good-sized nuke were employed.

Anyway, after 9/11 the authorities decided to build the highway bypass bridge several hundred yards downstream to eliminate the possibility of terrorists driving an 18 wheeler truck bomb across the old dam road.

 

 

Edited by Armybrat
Someone is hammering on my front door and shouting something. brb
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22 minutes ago, Armybrat said:

Abbey really was dreaming, as the reinforced concrete of Hoover Dam is 660’ thick at the base and tapers to 45’ thick at the crest,

Considering the level of Lake Meade is at least 100’ below the crest, and sinking a fleet of explosive-laden houseboats down to a thicker part of the dam, I’d say that venture would be nigh impossible, unless a good-sized nuke were employed.

Anyway, after 9/11 the authorities decided to build the highway bypass bridge several hundred yards downstream to eliminate the possibility of terrorists driving an 18 wheeler truck bomb across the old dam road.

 

 

I don’t know about that. The bouncing dambuster bombs employed by the British were quite a bit short of a nuclear blast, but the incompressibility of water made for giant hammer blows against the concrete. 

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11 minutes ago, Bobby_Batronic said:

I don’t know about that. The bouncing dambuster bombs employed by the British were quite a bit short of a nuclear blast, but the incompressibility of water made for giant hammer blows against the concrete. 

IIRC, those dambusters skipped into the top areas of the old dam they were used against....and the lake level there was near the crest.

Hoover is a different situation, especially with Lake Meade at very low levels at present.

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5 minutes ago, Armybrat said:

IIRC, those dambusters skipped into the top areas of the old dam they were used against....and the lake level there was near the crest.

Hoover is a different situation, especially with Lake Meade at very low levels at present.

Actually, they skipped to the damn and then sunk to somewhere near the base. Or that was the design anyway. The skipping was the only way they could devise to snuggle the weapons up close to the concrete as they sank. 

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11 minutes ago, Bobby_Batronic said:

Actually, they skipped to the damn and then sunk to somewhere near the base. Or that was the design anyway. The skipping was the only way they could devise to snuggle the weapons up close to the concrete as they sank. 

Yes, but those dams were only 100’ - 120’ thick at the base and 20’ at the crest. Small potatoes compared to Hoover. More like Mansfield, but smaller. Mansfield is twice as high & twice as thick as the German ones in WW2.

Edited by Armybrat
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1 minute ago, InkaUtexas said:

so how did your Lancaster handle? 

Heh, my Brit friend’s dad was a Lancaster pilot. He flew a lot of missions over France & Germany. On one sortie the flack killed a crewman and he barely was able to fly it back to England for a crash landing.

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21 minutes ago, Armybrat said:

Yes, but those dams were only 100’ - 120’ thick at the base and 20’ at the crest. Small potatoes compared to Hoover. More like Mansfield, but smaller. Mansfield is twice as high & twice as thick as the German ones in WW2.

Does the size of the base of the damn matter if the amount of water it’s holding back is proportionally larger? I dunno. But it would seem that you’d only need to start the failure to let the water behind do the rest. 

Edited by Bobby_Batronic
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52 minutes ago, Bobby_Batronic said:

Does the size of the base of the damn matter if the amount of water it’s holding back is proportionally larger? I dunno. But it would seem that you’d only need to start the failure to let the water behind do the rest. 

I dunno, but the engineers here could probably figure it out......Dutch Boy notwithstanding.

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3 hours ago, Armybrat said:

Yes, but those dams were only 100’ - 120’ thick at the base and 20’ at the crest. Small potatoes compared to Hoover. More like Mansfield, but smaller. Mansfield is twice as high & twice as thick as the German ones in WW2.

So you'd just need some sort of depth charge to blow it halfway down. Even if the rest didn't come down it would do pretty serious damage.

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Still don’t know if that would work.

Take note that the Germans built several submarine bases in France & Italy during WW2 out in the open with 20’ thick walls & roofs. Even after intensive allied bombing they were relatively unscathed, functioning to the end of the war. They are still there today.

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Come on, man.  Dude gets inside, and with a few well-placed charges, he cracks the dam, and lets the hydrostatic pressure do its work on those cracks, and BLAMMO, the whole thing goes down.
Am I the only one around here who's seen Force 10 from Navarone, goddamit?  AM I?
poster-780.jpg
 

That’s some heavy duty dog doo-doo!!
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13 minutes ago, Brisketexan said:

Come on, man.  Dude gets inside, and with a few well-placed charges, he cracks the dam, and lets the hydrostatic pressure do its work on those cracks, and BLAMMO, the whole thing goes down.

Am I the only one around here who's seen Force 10 from Navarone, goddamit?  AM I?

poster-780.jpg

 

Hey, I was in on page 1!!

Quote

I bet it's Harrison  Marshall Ford in Force 10 from Riverbend,.

 

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